The present invention relates to a non-clutch compressor for employment in an automobile chilling unit.
Known refrigerant compressors for employment in an automobile chilling unit are driven directly by an engine through an electromagnetic clutch and belt in the following manner. The field core of the electromagnetic clutch is energized when the operation of the compressor is required, and a friction plate called an armature is attracted to a rotor pulley by magnetic force to transmit driving force from the engine to a shaft of the compressor. On the other hand, the energizing of the field core is stopped when the operation of the compressor is not required, and only the pulley races.
Recently, refrigerant compressors capable of changing their cooling capacity by themselves have come in to practice. Of the compressors, oscillating swash plate type compressors can change the stroke of the piston within 5-100% by changing the pressure in the crank chamber and have high capacity control efficiency.
On the basis of oscillating swash plate type compressors, various types of compressors having no conventional electromagnetic clutch, which are called non-clutch compressors, have been proposed. For example, such a compressor is disclosed in Japanese Laid-open Patent Publication No. 62-191673, as shown in FIG. 5.
The compressor disclosed therein is of the variable capacity type, and is so constructed that adjustment of the pressure in a crank chamber 2 accommodating an oscillating plate 1 causes the incline angle of the plate 1 to change, so that the discharge capacity can be changed. As shown in FIG. 6, the variable capacity type compressor, the oscillating swash plate type compressor, comprises first and second passages 4 and 5 independently arranged therein and connecting the crank chamber 2 with a suction pressure chamber 3. A third passage 7 connects the crank chamber 2 with a discharge pressure chamber 6. A pressure control valve 8 is arranged in the first passage 4, closing when the pressure in the suction pressure chamber 3 is less than a predetermined set value and opening when the pressure is not less than the value to connect the crank chamber 2 with the suction pressure chamber 3 through the first passage 4. A change valve 9 is provided for closing the first passage 4 and opening the second and third passages 5 and 7 when the pressure in the discharge pressure chamber 6 is less than a predetermined set value, and opening the first passage 4 and closing the second and third passages 5 and 7 when the pressure in the discharge pressure chamber 6 is not less than the values. A throttling mechanism is arranged in the second passage 5 and throttles flow so that the cross-sectional area of the second passage 5 is less than that of the third passage 7.
The necessary conditions under which the non-clutch compressor comes in to practice are as follows: (1) it can assure the reliability and durability of the compressor not less than those of a compressor with an electromagnetic clutch; (2) it can prevent fuel consumption drop throughout the year even though it is always operated; (3) the parts added instead of an electromagnetic clutch have no disadvantage in configuration and cost.
With respect to the above conditions, every mechanisms presently proposed may not be realized. It appears that for example, it is required for the above-described known compressor to remedy some disadvantages, such as problems concerning a lubricating method of parts in the compressor in addition to a complicated pressure control construction in the crank chamber thereof.
In order to realize the non-clutch compressor, it is required to remedy the lubricating problems such as wear, burning, and degradation of sealing of parts in the compressor by only adding smaller and lower-cost parts. Furthermore, since the compressor is operated even though the cooling operation is not required, it is constructionally required to greatly reduce the cooling capacity and the load power at that time.